Magnesium?

[Reefer08]

Currently my alkalinity and calcium are in good parameters. Does this mean I shouldn't test for Magnesium? My Calcium stays around 450 and my alkalinity typically is 10dkh.

According to RANDY HOLMES-FARLEY

Whatever supplement you choose, I’d suggest targeting the natural seawater concentration: 1285 ppm. For practical purposes, 1250-1350 ppm is fine. I would not suggest raising magnesium by more than 100 ppm per day.

The problem is that for every magnesium ion released from the dolomite, 2 units of alkalinity are also released:


Consequently, if one wants to raise magnesium by 100 ppm, the alkalinity will necessarily rise by 8.2 meq/L (23 dKH). The only way around this problem is to add a mineral acid (not vinegar) to the aquarium to reduce the alkalinity, and that may be more problematic than just adding magnesium in the first place.

So does this mean that I can't raise my magnesium because it will raise my alkalinity? Wouldn't it be safe to estimate that my magnesium is at NSW levels if my CA/ALK is balanced?

Thanks

[snorvich]

There are other ways to raise magnesium other than dolomite in your ca reactor. Go back and read Randy's article at:

http://reefkeeping.com/issues/2006-07/rhf/index.php

[reef_doug]

I wouldn't try to raise Mg via the CaRx route. I would use Randy's recipie 10:1 for raising Mg (version 3 towards the bottom)
http://reefkeeping.com/issues/2006-07/rhf/index.php#14
Alternatively Kent Tech M is good for an over the couter supplement.

Once Mg is inline around 1300 you could look at ZEO mag or something else to supplement the Calcium Reactor media to maintain the Mg level.